The subject matter of the instant invention relates to polyurethane foam formulations and methods for making polyurethane foams.
The development of additives that can improve physical properties of polyurethane foam is of great interests because these additives can enable the use of more environmentally friendly components necessary to make polyurethane foam without sacrificing the mechanic performance of the finished product. Polyurethane foam is produced by reaction of polyisocyanate with polyol in the presence of a catalyst, typically tertiary amine. Unfortunately, tertiary amine catalysts can be malodorous and may have high volatility due to their low molecular weight. To overcome this problem, polyurethane manufacturers have sought to achieve amine emission-free products by using non fugitive tertiary amine catalysts. The retention of a tertiary amine in polyurethane foam can be due to the low volatility of the amine or more typically the tertiary amine would become part of the polyurethane polymer if the tertiary amine contains an isocyanate reactive group. Whether the low volatility is due to the intrinsic property of the amine or because of its incorporation in the polyurethane polymer, the presence of these tertiary amines in the finished product may cause the polyurethane polymer to undergo degradation when exposed to heat and humidity.
U.S. Pat. No. 4,258,141 discloses a process for the manufacture of flexible polyurethane foam with cyanic acid derivatives. The invention relates to a process to make flame resistant flexible polyurethane foams by reacting a mixture of diphenylmethane diisocyanates and polyphenylene polymethylene polyisocyanates having a functionality greater than 2 containing 40 to 90 percent by weight diphenylmethane diisocyanate based on the total weight of said mixture; polyol, cyanic acid derivatives such as cyanamide, dicyanamide, guanidine, biguanidine, melamine, cyanuric alkyl esterhydrazides and amides as flame inhibitors, and blowing agents, as well as, possibly, chain extenders and other additives. The cyanic acid derivatives are added to the foamable polyurethane mixture in quantities of 10 to 70% by weight, preferably 20 to 50% by weight, based on the weight of the mixture of isocyanates. These high levels of cyanic acid derivative are added to the reactive mixture as suspensions and are necessary to ensure flame resistance. Thus according to this invention at least 4.6 pphp of cyanoguanidine is needed in TDI based foam and at least 5.9 pphp of cyanoguanidine is neede in MDI foam. The poor solubility of cyanoguanidine in the reactive mixtures requires this material to be dispensed as a suspension rather than in solution.
U.S. Pat. No. 3,931,064 discloses an isocyanate based polymeric foam material having dispersed particulate low-softening point inorganic oxide glass having a transformation temperature of not greater than 300° C. and optionally a blowing agent which is capable of liberating a non-flammable gas on heating above a temperature in the range of 150 to 400° C. The invention relates to the incorporation of low softening point glass, particularly a phosphate glass, into an isocyanate-based foam and especially into a rigid isocyanate-based foam which confers a degree of fire retardance and may also give less smoke generation on combustion of the foam than the combustion of foams containing conventional fire-retardants additives.
US Pat. Application Pub No. 2007/0197672 A1 discloses foamable one part polyurethane compositions containing a high functionality quasi-prepolymer and a hydrated salt.
The previously identified patents and patent applications are hereby incorporated by reference.